Facet-Engineered Pt Redispersion on CeO ₂ : Unraveling Morphology and Pt Density Effects for Tailored CO and C ₃ H ₈ Oxidation Catalysis

The thermal stability of Pt-based catalysts, which is pivotal for air pollutant abatement, is dictated by a delicate balance between nanoparticle sintering and redispersion into single atoms. Probing the intrinsic interaction between Pt and CeO2 crystal facets at comparable Pt surface densities to precisely control these dynamic structural transformations remains a grand challenge. Herein, we synthesized uniform Pt nanoparticles and supported them on CeO2 with different morphologies exposing distinct crystal facets, aiming to investigate the influencing factors and critical conditions for the redispersion behavior of Pt nanoparticles induced by CeO2 morphology. Catalytic performance for CO and C3H8 oxidation was used for evaluation. The results revealed a pronounced facet-dependent SMSI effect. The rCeO2 (110) facet exhibited the strongest interaction, inducing Pt cluster redispersion to single atoms efficiently at a notably low 400 °C. In contrast, the oCeO2 (111) facet showed the weakest interaction, failing to promote effective Pt redispersion into single atoms even at 600 °C, while cCeO2 displayed intermediate behavior with redispersion at 500 °C. Crucially, we demonstrate that the initial theoretical Pt atomic density, influenced by the support’s specific surface area, acts as a critical threshold (1 atom nm–2), significantly affecting apparent redispersion. By carefully adjusting Pt loading to control this density, we confirmed that redispersion trends are intrinsic to the facet-metal interface. The Pt state profoundly influenced the activity in a reaction-dependent manner. For CO oxidation, over-redispersion on rCeO2 could diminish low-temperature activity. Remarkably, for propane oxidation, the 0.275Pt/oCeO2 catalyst, which resisted redispersion and maintained stable particulate Pt, exhibited superior thermal stability. After calcination at 400 and 600 °C, its T50 for CO and C3H8 decreased minimally by only 20 and 3 °C, respectively. These findings challenge the notion that maximal single-atom dispersion universally optimizes the performance, offering a rational framework for designing highly stable and active Pt/CeO2 catalysts via precise facet engineering and Pt loading optimization.